This invention relates generally to curable coating compositions and insulating films prepared therefrom. More particularly, it relates to spin-coating compositions comprising phosphorus-doped and/or boron-doped silsesquioxane-based copolymers. The fully cured novel copolymers essentially have the general formula EQU [(Ar.sup.1 SiO.sub.1.5).sub.k (Ar.sup.2 PO.sub.2.0).sub.m (Ar.sup.3.sub.p BO.sub.q).sub.n ]
European Patent Application 0049127 (published Apr. 7, 1982 and assigned to Fujitsu) relates to the preparation and use of certain ladder-type organosiloxanes having utility as interlayer dielectric films in integrated circuits based upon semiconductors. In particular, see Example 6 and claim 2. There is no disclosure relating to such polymers that are phosphorus-doped or boron-doped.
A computer search of Chemical Abstracts failed to disclose any references which related to silsesquioxane-phosphorus compounds.
Elementary parts of integrated circuits have previously been doped with phosphorus and boron. For example, see aforementioned Fujitsu's Example 6 and FIG. 7. Also see U.S. Pat. No. 3,825,442 (Moore).
"Spin-On BPSG and Its Application to VLSI" is the title of a paper to be presented at a meeting of The Electrochemical Society in the middle of May, 1985 in Toronto, Ontario, Canada. Its authors are S. L. Chang, K. Y Tsao, M A. Meneshian, and H. A. Waggener, AT and T Teletype Corp., Skokie, Ill. 60077. The pre-presentation summary abstract states
"Recently, there has been much interest in the use of borophosphosilicate glass (BPSG) for fusing tapering application in VLSI fabrication. A new method to obtain the BPSG film by using the spin-on liquid doping glass which contains boron and phosphorus. From the experimental results, it is feasible to use the spin-on BPSG film as an intermediate dielectric layer to provide a planarized and smooth surface for IC fabrication."
Essentially, the now-known prior art fails to disclose (1) the specific interlayer dielectric film claimed hereinafter; (2) the specific spin-coating composition required to spin-coat an acceptable film on conventional equipment; (3) the processing conditions required to prepare the spin-coating composition; and (4) the ranges of processing conditions required during spin-coating in order to obtain an interlayer dielectric film having the desired combination of properties.